Assessing the potential for biological invasion - the case of Ammophila arenaria in South Africa

Many plants, especially woody species, introduced into South Africa for orn amental or commercial purposes, have become invasive in a number of habitat s. Because of the risk of an invasion of coastal dunes by yet another speci es, the European dune grass Ammophila arenaria, used as a dune stabilizer, is assessed using lists of attributes of invasive species and invasible eco systems. It is impossible to predict plant invasions, but both invasive spe cies as well as invaded ecosystems are often characterized by certain attri butes which facilitate invasions. Many of the species attributes connected with invasion appear to apply to A. arenaria. Above ail, the grass is chara cterized by ecological tolerance and Vigorous rhizomatous reproduction. An important site attribute connected with invasion is an evolutionary history with isolation patterns, which applies to the South African Cape coast. We conclude also on the basis of the overseas experience, that the potential for A. arenaria to become invasive needs urgent investigation in the South African context.